Generally, when such strainers are used in a fluid, the strainer assembly is submerged into the fluid and always must have a means of connecting to a hose, piping or to a fixture, hereinafter called a “draw line”. Strainers generally use a strainer medium formed from perforated sheets of specified orifice or openings or, as in the case of Avery et al. U.K. Patent No. 2,318,305, from a woven strands of material. The construction proposed by Avery et al. presents difficulties in that a woven material may be prone to tearing or dislocation of certain of the strands of strainer medium, making the strainer less effective. As well, constructing such a strainer, by weaving the fabric, is a laborious and time consuming process, resulting in a relatively expensive product.
Problems encountered with perforated sheets of specified orifice or openings include the creation of vortexes which, reduce the efficiency of the draw line. A vortex is defined as a whirling mass of fluid forming a vacuum at its center, into which anything caught in the motion is drawn. Natural vortexes caused by draw fluids are to be avoided where possible, since larger vortexes tend to draw more debris and clog up the strainers more quickly.
It is an object of the present invention to provide an improved draw line strainer which is economical to manufacture and effective in operation.